Re: [RFA] namespaces and vendor extensions

From: Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org>
To: "Joshua (Shiwei) Zhao" <swzhao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Radiotap <radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org>,
	Gerald Combs <gerald-IZ8446WsY0/dtAWm4Da02A@public.gmane.org>
Subject: Re: [RFA] namespaces and vendor extensions
Date: Tue, 01 Dec 2009 10:16:51 +0100	[thread overview]
Message-ID: <1259659011.32171.45.camel@johannes.local> (raw)
In-Reply-To: <d521a2310911301441l3c5503b5hf43d31a47e83fe4b-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

[-- Attachment #1: Type: text/plain, Size: 835 bytes --]

Joshua,

> For the structure of the vendor space, you extend 'skip_length' from 8
> bits to 16 bits.
> > Structure
> >        u8 OUI[3], u8 sub_namespace, __le16 skip_length
> I'm neutral on that. My question is why not extend 'sub_namespace' to
> 16 bits too? 

I don't see much point in having more than 255 sub-namespaces per OUI,
do you?

> I hardly see that a vendor extension part can go over 255
> bytes. But if that happens, it's quite likely that the extension may
> contain more than 8 fields.

Where are you taking 8 fields from? After the vendor extensions bit, the
vendor extension puts vendor-defined presence bits into the it_present
bitmap. Therefore, you have an unlimited number of fields per vendor
sub-namespace, as such I see little reason to support more than 255
sub-namespaces.

johannes

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 801 bytes --]